Climatic Data, Instrumental Records

DETECTION OF CURRENT global temperature and reconstruction of past trends rely on data from four sources: surface temperature from weather or climate stations, weather balloons, satellite mounted remote sensors, and proxy sources. Data from the first three categories are known as the instrumental record.

Until recently, measurements of global air-temperature change were based entirely on measurements taken on the ground at weather stations. Three authorities that have taken responsibility for the combined surface record are the Climate Research Unit (CRU) of the University of East Anglia (UEA), the National Aeronautics and Space Administrations (NASA's) Goddard Institute for Space Studies (GISS), and the Global Historical Climate Network (GHCN) run by the U.S. National Océanographie and Atmospheric Administration (NOAA).

Given that the data come from weather stations unevenly distributed ...